In general silver halide color photographic materials are spectrally sensitized with silver halides and sensitizing dyes in accordance with the three color separation process, and a yellow coloring coupler is incorporated into the blue-sensitive silver halide emulsion, a magenta coloring coupler into the green-sensitive silver halide emulsion, and a cyan coloring coupler into the red-sensitive silver halide emulsion. After imagewise exposed, the materials are processed with a color developer containing a p-phenylenediamine derivative as a color developing agent and then bleach-fixed to provide color images.
The color images thus-formed in such silver halide color photographic materials are often stored under exposure to light for a long period of time, or are sometimes stored in the dark also for a long period of time, though the time for exposure to light may be short in the latter case. It is well known that such color images often become seriously faded depending upon the conditions during storage. In general, the color fading in the former case is called "light fading", and that in the latter case "dark fading". When color photographic materials after processing are to be stored as recording media semipermanently for a long period of time, it is desired that the degree of such light fading or dark fading is minimized, at least so that the systematic three color fading balance of the respective yellow, magenta and cyan color images may be maintained to correspond to the original color balance therebetween. However, there is known a disadvantageous phenomenon that the respective colors of yellow, magenta and cyan of photographic color images differ from one another in the degree of the light fading and the dark fading of the respective colors, so that, after the color images have been stored for a long period of time, the systematic three color fading balance is often lost, and the image quality of the color images formed is thereby deteriorated.
In general, the degrees of light fading and dark fading naturally differ, depending upon the couplers used as well as other various factors. However, with respect to the dark fading for dyes in many color photographic materials, the color fading is more noticeable in a cyan color image, a yellow color image, and a magenta color image, in the order listed, and, particularly, the degree of the dark fading of a cyan color image is the most noticeable as compared with the other color images. With respect to the light fading of color images formed, the color fading is apt to be more noticeable in a cyan color image, a yellow color image, and a magenta color image, in the order listed, with respect to a light source strong in ultraviolet radiation.
Under these circumstances, it is believed necessary to suppress the dark fading of the cyan color image as much as possible, so as to maintain a well-balanced color fading balance of the three colors of yellow, magenta, and cyan in color images for a long period of time, and, therefore, various studies have hitherto been made for improvement of the light fading and dark fading properties of color images. The studies may be grouped into two types; one has been to develop new couplers capable of forming color images which are hardly faded, and the other has been to develop new additives capable of effectively inhibiting fading of color images formed.
Many phenolic cyan couplers capable of forming cyan dyes are known. For example, 2-[.alpha.-2,4-di-tert-amylphenoxybutanamido]-4,6-dichloro-5-methylphenol described in U.S. Patent 2,801,171 can form a color image with a good light fastness, which, however, is known to have a defect in that its heat resistance is poor.
Phenolic cyan couplers where the 3- or 5-position of the phenol nucleus is substituted by an alkyl group having 2 or more carbon atoms are described in, for example, JP-B-49-11572 and JP-A-60-209735 and JP-A-60-205447 (the term "JP-B" and "JP-A" as used herein means an "examined Japanese patent publication" and an "unexamined published Japanese patent application", respectively). Although the cyan images to be formed from these couplers have been improved in the heat resistance in some degree, the improvement is still not totally sufficient.
2,5-Diacylaminophenol cyan couplers where the 2- and 5-positions of the phenol nucleus are substituted by acylamino groups are described in, for example, U.S. Pat. Nos. 2,369,929, 2,772,162 and 2,895,826, and JP-A-50-112038, JP-A-53-109630 and JP-A-55-163537.
These 2,5-diacylaminophenol couplers may form cyan images with good heat resistance. However, these still have some drawbacks in that the coloring property of the couplers is poor, the light fastness of the cyan images to be formed therefrom is poor, and the non-reacted cyan couplers cause yellowing under light. In addition, further improvement of the heat resistance of the couplers is desired.
1-Hydroxy-2-naphthamide cyan couplers are generally insufficient in both light fastness and dark fastness properties.
The 1-hydroxy-2-acylaminocarbostyryl cyan couplers described in JP-A-56-104333 can form color images having good fastness to light and heat, but have problems in that the spectral absorption characteristics of the color images formed is unfavorable for color reproduction of color photographs and the color images formed form pink stains after exposure to light.
The cyan polymeric couplers described in U.S. Pat. No. 3,767,412 and JP-A-59-65844 and JP-A-61-39044 are surely excellent in heat resistance under dry conditions, but are defective in that the heat resistance under high moisture conditions is poor, and the coloring property is insufficient.
U.S. Pat. No. 4,203,716 describes a method of dissolving a hydrophobic substance such as oil-soluble coupler in a water-miscible organic solvent and blending the resulting solution with a loadable polymer latex so as to load the hydrophobic substance onto the polymer. However, there is a problem in that such method of using a loadable polymer latex is inferior to the case of using a water-immiscible high boiling point organic solvent with respect to the light fastness of the cyan image to be formed. Moreover, there is another problem in that a large amount of a polymer would be required to be used in order that the coupler could be sufficiently loaded to obtain a sufficient maximum color density.
JP-B-48-30494 describes that photographic materials containing an emulsified dispersion of a coupler formed by the use of a homopolymer of organic solvent-soluble hydrophobic monomers having a particular structure or a copolymer of the said monomers with hydrophilic monomers having a particular structure, in place of using any high boiling point coupler solvents, the grain size of the grains dispersed in the emulsified dispersion being in the range of from about 0.5 .mu.m to about 5 .mu.m have been improved with respect to the film quality, recoloration failure and light fastness as well as the storability before processing.
However, we the present inventors have found that the use of such homopolymer of hydrophobic monomers described in the aforesaid JP-B-48-30494 in place of coupler solvents involves various problems such as that the coloring property of the couplers is poor, and the stability of the emulsified dispersion is poor. In particular, the poor coloring property was found noticeable when the emulsified dispersion-containing photographic materials were processed with a developer not containing any development accelerator, such as benzyl alcohol, which was added to the developers used in examples of the said JP-B-48-30494. On the other hand, the copolymers with hydrophilic monomers such as acrylic acid could surely be effective for somewhat improving the stability and coloring property of the resulting emulsified dispersions, but the improvement is considered still insufficient. In addition, there would occur another problem that the fading resistance (especially fading resistance under high heat and moisture conditions) is to be worsened if the proportion of hydrophilic monomers in the copolymer is increased so as to improve the coloring property of the resulting emulsified dispersion. Any way, since all the homopolymers and copolymers are poor in the ability of preventing crystallization of couplers, there is an additional disadvantageous problem that the coupler in the emulsified dispersion would form crystals during storage thereof.
When the technique as illustrated in JP-B-48-30494 is applied especially to cyan couplers, there is a significant problem in that the light fastness is extremely worsened (reduction of from 1.5 to 3 times) as compared with the case of dispersing the couplers in a conventional high boiling point solvent (so-called "oil dispersion").
In addition, the technique of JP-B-48-30494 has another problem, in that although the hue of the cyan image formed is in a long wavelength range immediately after developed, this tends to easily shift into a short wavelength range, especially after storage under high temperature conditions. The problem means that the hue of the image formed would change time-dependently.
As mentioned above, the couplers whose dark fastness has been improved by variation of the coupler structures of themselves by the prior art techniques (dark fastness-improved couplers) are noted to be frequently insufficient in the points of the color hue, coloring capacity, generation of stains and light fastness. Accordingly, a novel technique capable of overcoming the foregoing prior art problems and satisfying the necessary points mentioned above is being desired. On the other hand, effective and harmless dark fastness-improving means have not been found up to the present, from the aspect of the means of using couplers, by improvement of the additives to be used, as well as by the means of dispersing couplers.
Coloring of photographic emulsion layers and other layers is often conducted for the purpose of absorbing a light with a particular wavelength range in silver halide color photographic materials.
For the purpose of preventing blurring of an image formed on a photographic material, which can be caused by the phenomenon that the light passing through the photographic emulsion or after passed therethrough is scattered and is reflected on the interface between the emulsion layer and the support or on the surface of the photographic material opposite to the emulsion layer and thereafter is again introduced into the photographic emulsion layer, or that is, for the purpose of preventing a so-called halation, a colored layer may be provided between the photographic emulsion layer and the support or on the surface of the support opposite to the photographic emulsion layer. Such colored layer is called an antihalation layer. In the case of multilayered color photographic materials, such antihalation layer may be provided between the multiple layers.
In order to prevent the lowering of the image sharpness because of the light scattering in photographic emulsion layers (the phenomenon is generally called irradiation), the photographic emulsion layers may be colored.
The layers to be colored often contain a hydrophilic colloid in many cases, so that a water-soluble dye may be incorporated into the layers for coloration thereof. The dyes to be used for this purpose are required to satisfy the following conditions.
(1) They have a proper spectral absorption in accordance with the intended use thereof.
(2) They are photochemically inactive. That is, they do not have any chemically harmful influences, such as lowering of sensitivity, fading of latent images, or fogging, on the properties of silver halide photographic emulsions.
(3) They are decolored or dissolved out by photographic processing, so that they do not give any harmful coloration on the photographic materials processed.
Those skilled in the art have variously studied so as to find out dyes which satisfy the said conditions, and, as a result, a number of dyes have been known. Examples include oxonol dyes having pyrazolone and barbituric acid nuclei, as described in British Patents 506,385, 1,177,429, 1,311,884, 1,338,799, 1,385,371, 1,467,214, 1,433,102 and 1,553,516, JP-A-48-85130, JP-A-49-114420, JP-A-55-161233 and JP-A-59-111640 and U.S. Pat. Nos. 3,247,127, 3,469,985 and 4,078,933; and other oxonol dyes as described in U.S. Pat. Nos. 2,533,472 and 3,379,533 and British Patent 1,278,621.
Among them, oxonol dyes having two pyrazolone nuclei have been used as useful dyes for dyeing photographic materials, as these are easily decolored in a sulfite-containing developer, and thus have hardly any adverse influence on photographic emulsions.
However, some dyes of this type have drawbacks, in that although they have little influence on the photographic emulsions themselves, that these would cause spectral sensitization in an undesired range for spectrally sensitized emulsions or would cause lowering of sensitivity of such emulsions, the latter being considered to result from desorption of the sensitizing dye from the emulsion.
In addition, some of said dyes would remain in the photographic materials processed, depending upon the rapid processing, which is frequently carried out these days. In order to overcome the problem, it has been proposed to use dyes having a high reactivity with sulfite ion. In this case, however, the stability of the dyes used is insufficient in the photographic film, with the result that the concentration of the dyes is lowered after storage, and the intended photographic effect is not attained thereby.